Multiplexing-oriented plasmon-MoS2 hybrid metasurfaces driven by nonlinear quasi bound states in the continuum

Qun Ren,Xiaofei Xiao,Quan Xu,Jianwei You,Feng Feng,Wei E I Sha,Zhihao Lan,Xiang Yao,Ming Xin

doi:10.1364/oe.414730

Abstract

Rapid progress in nonlinear plasmonic metasurfaces enabled many novel optical characteristics for metasurfaces, with potential applications in frequency metrology [Zimmermann et al. Opt. Lett. 29:310 (2004)], timing characterization [Singh et al. Laser Photonics Rev. 14:1 (2020)] and quantum information [Kues et al. Nature. 546:622 (2017)]. However, the spectrum of nonlinear optical response was typically determined from the linear optical resonance. In this work, a wavelength-multiplexed nonlinear plasmon-MoS2 hybrid metasurface with suppression phenomenon was proposed, where multiple nonlinear signals could to be simultaneously processed and optionally tuned. A clear physical picture to depict the nonlinear plasmonic bound states in the continuum (BICs) was presented, from the perspective of both classical and quantum approaches. Particularly, beyond the ordinary plasmon-polariton effect, we numerically demonstrated a giant BIC-inspired second-order nonlinear susceptibility 10-5m/V of MoS2 in the infrared band. The novelty in our study lies in the presence of a quantum oscillator that can be adopted to both suppress and enhance the nonlinear quasi BICs. This selectable nonlinear BIC-based suppression and enhancement effect can optionally block undesired modes, resulting in narrower linewidth as well as smaller quantum decay rates, which is also promising in slow-light-associated technologies.

Highlights

Nonlinear metasurface is a promising research orientation for diversifying the optical signal processing functions[4,5]
Since the nonlinear optical resonance was typically decided by the linear optical response, new theories are to be explored for more novel functionalities such as individually cancelling particular noise in the nonlinear optical spectrum
Since practical applications are limited to the quasi-BIC regime, in the following discussions, we will use the actual permittivities of metals to study the linear and nonlinear optical responses of the proposed metasurfaces

Summary

INTRODUCTION

Nonlinear metasurface is a promising research orientation for diversifying the optical signal processing functions[4,5]. A nonlinear device exhibits constant nonlinear susceptibility in the frequency range far away from the resonance conditions of the material Metasurfaces may break this limitation utilizing its design flexibility at the nanoscale level, so as to obtain ultra-high nonlinear susceptibilities in several desired wavelength windows, within a compact physical structure. Most importantly, when TMD is placed at the hot spots of quasi-BICs, the strongly enhanced localized field induced by plasmons could greatly excite the optical nonlinearity of TMDs. Inspired by the ideas above, here we propose a plasmon-MoS2 hybrid nonlinear metasurface with multiple radiation channels induced by selectable suppressed and enhanced plasmon-polariton resonance and BICs, which enables optional high nonlinear conversion efficiency at several wavelength windows.

PRINCIPLE OF QUASI-BIC RESONANCE ENHANCEMENT

Quantum and classical explanation of quasi BIC in plasmon-MoS2 metasurfaces

Enhanced nonlinear optical channels in communication band

Suggested Fabrication Process

CONCLUSION